What Causes Cramps In The Abdomen After Taking I Pill?

So the last time i had unprotected sex was 30th december. My bf didnt ejaculate inside me but as i read some sperms may still have gotten inside. I had an ipill (emergency contraceptive pill) straight after though. I ve had 4 negative pregnancy teste so far and i ve had 2 periods which have been normally heavy however my last period gave me more stomach cramps than usual and also i have a constant mild stomach pain for the last month however i have no other symptoms of pregnancy. All my period pains such as painful breasts went away when my periods finished and are still gone. Do u think i may still be pregnant? My periods are usually irregular so before sex i had it on 27th november and then 7th january and then 26th feb.